1. Related Field
The present invention relates generally to semiconductor integrated circuits. In particular, the present invention relates to a redundant input/output buffer for communication of data with a semiconductor integrated circuit.
2. Description of the Related Art
Integrated circuits (“IC's”) are commonly encased in an IC package, commonly referred to as an IC chip. The IC package has multiple external pins, or leads, that are made of a conductive material and provide an electrical connection for the IC resident within the IC package to external circuits. Each pin is coupled with various input, output, or input/output nodes of the IC. Common connections to the IC package include data input, output and/or input/output pins (“I/O pins”), a voltage supply terminal (VSS) and a ground terminal. The size, orientation, and arrangement of the pins may conform to conventional standards for the type of IC, or other conventional IC package standards.
The IC package may enclose various types of IC's. The IC package may include a resident, or main, IC as well as input, output, and/or input/output circuits (“I/O circuits”), such as a data buffer circuit, current surge and electrostatic discharge (ESD) protection. The resident IC may be a processor, a memory circuit, logic gates, latches, resistive or capacitive elements, or any combination of known electronic components commonly fabricated using known fabrication techniques. The resident IC is connected to the external pins through the I/O circuits. Data can be communicated with the IC via an electrical connection to the external pins and the I/O circuits.
A failure in the I/O circuits may occur, for example, when an electrostatic discharge (ESD) may be inadvertently applied to the external circuit to which the IC is connected. When the I/O circuit fails, the data that are to be communicated via the failed I/O circuit may not be capable of being communicated with the resident IC, and therefore, the IC may not function properly. When an ESD failure, or other electrical failure occurs, the result is often a malfunctioning or non-functioning device in which the IC is operative. The failure often requires replacement of the entire IC package to restore proper operation of the device. Replacement of IC packages such as memory devices and processors is often expensive and may be cost prohibitive. The resident IC may remain functional, but because the I/O circuit of the IC package is not separable from the IC package, the entire package may need to be replaced.
Accordingly, there is a need in the art to provide a spare input/output buffer circuit for an IC environment.